Use good data when buying additives, fertilizers

Larry Oldham | May 21, 2004

With fertilizer costs following the energy market higher, some producers may be tempted to explore non-traditional soil additives and fertilizers. Many such materials will not cause agronomic problems, but do they actually provide agronomic and economic benefits?

Several laws and regulations are in place in Mississippi to protect producers. All brands and grades of fertilizer, lime, and soil/plant amendment products must be registered with the state agriculture department and the state chemist before they can be sold in Mississippi.

Part of the registration process is an evaluation of product claims and background research by a qualified review committee. However, there is inadequate or no research data for some products. This lack of data is due to several factors, including that some products have never been objectively evaluated by independent scientists.

By Mississippi regulation, the supporting research must have been performed in soils and climates similar to conditions in the state. Without this documentation, it is difficult for products to become registered in the state.

According to reports from the fields, despite this layer of consumer protection, some non-traditional materials are commercially available. How should a producer evaluate whether a product has merit?

Listen carefully for claims such as “small amounts work wonders.” For example, soil activators at 1 to 2 gallons per acre to stimulate microbial activity. Inoculation of seed with bacteria to promote nodulation in legumes is well-characterized and continues to be cost-effective. What has not been characterized or proven by research is non-specific microbial stimulation by any other means than the addition of several hundred pounds of organic matter.

Some fertilizers will be advertised as 100 percent available to the plant. Common urea-ammonium nitrate solution and other fertilizers are also 100 percent available; otherwise, they could not have been registered for sale.

Another issue is the promotion of lower application rates because of the high nutrient availability. However, remember yields will be lower if you actually needed more nutrients.

Ask questions. Has this product been university tested? Often the answer is no, because (a) the university only wanted to raise money by charging for the research, or (b) it is too new for the university to know about. Both answers should be discounted.

Fertilizer products are rarely developed in a vacuum. Extensive information is exchanged among soils specialists and agronomists in the region and across the nation. These people are paid by the public and work for the public good to provide fair, objective, science-based information.

Ask for multiple years' data over multiple locations, with several soil types and management situations. If the product has been registered in Mississippi, the information should be available.

Testimonials are suspect. Pictures without labels, stories about yields without statistics, and non-replicated field trials are common tactics used to sell products for which the science background is suspect. A very good rule of thumb: Never buy a product based on this type of information. Remember to request real data.

Resist pressure tactics and use common sense. Prices good only for today or for a week are a tipoff that something may not be “just right.” Develop a good trust relationship with the consultants, Extension personnel, and established commercial concerns familiar with your farm, soils, and production system.

Plan long ahead for your crop production needs, and price all fertilizer materials on the cost per pound of nutrient. If something is too good to be true, it probably is not.

Larry Oldham, Ph.D., is a soil specialist with the Mississippi State University Extension Service.